Cordtype electric switch



May 17, 1938. F, LOBL 2,117,966.

CORD TYPE ELECTRIC SWITCH Filed Nov. 21, 1935 member, the two members being pivotally sup-,

Patented Mi,- 11 1938 UNITED STATE 5 PATENT OFFICE This invention relates to electric switchu and particularly to so-called cord switches adapted to be inserted in the flexible cord of an electric heating pad, for instance, to connect the heater elements of the pad selectively singly and also in parallel in'the circuit, whereby to vary the heat. The switch of the present invention is in the nature of an. improvement on the switch disclosed in my copending application, Serial No. 28,506, filed June 26, 1935, and has as an object therefor to improve, simplify and cheapen the construction of the switch of said application.

7 For the purpose of connecting the two, usually, heating elements of an electric heating pad in parallel, it is necessary to make connection at the same time between a line conductor and the two terminals of the heating elements, and the element should be positive and each uninfluenced by the other. It has been proposed, heretofore, to provide two switch members movable conjointly but each structurally independent of the other for this pm'pose. It is an object of the present invention, however, to accomplish the functions of the two separate switch members more simply with one munber having two contact arms so arranged, and the cooperating stationary contact members also arranged. that the engagement of me arm with its stationary contact member dos not deleteriously influence the security of the engagement between the other arm and its cooperating contact member. I v

Another object of the invention is the provision of a movable switch member and an actuating ported upon a common pivot pin and connected for conjoint angular t thereabout but being otherwise free from mutual constraint so that the-switch member can flex freely and independently of the. 'actuaflng member in making the upper part or cover ill and the lower part or base II, the two parts beingsecured removably together by screws II. The cover is provided with an arcuate slot it through which is extended a part of the switch actuating mechanism terminated in a button It which can be positioned manually in any selected one of a plurality of positions corresponding to low, intermediate and high heats and end positions corresponding to circuit open positions of the switch.

. The switch mechanism is carried by a single relatively thin insulating plate 20 received and suitably positioned and supported within the enclosing casing. The front face of the plate, shown in Fig. 2, carries the switch mechanism while the back face, shown in Fig. 3, carries the circuit connections and line and" pad terminals.

The switch plate is provided witlf three stationary contact members 22, 24, 26, preferably in the form of tubular eyelets which pass-through the plate and are arranged in an arcuate line equally spaced from each other at the upper middle part of the plate. similar stationary contact member 28 disposed within the arcuate line of the other contacts and located at one side of the plate in the lower portogether electrically by a generally U-shapedtion thereof.

The contact members 22 and 26 are connected ,member II by a connecting plate 34 through which the eyelets which constitute said contact.

members are and over which they are headed. Said plate is provided with an upwardly directed extension I. which is located near the top ofthe supporting plate in an arcuate line with the terminal screw 3! and is screw-threaded to receive a terminal screw 3..

The incoming pair of line conductors are adapted to be connected with terminal screws 40 and '42 which are located at the bottom part of the insulating plate and' are screw-threaded into straps It and 4 respectively on the back face of said insulating plate. The strap extends to the upper part of said plateand is screwthreaded to ive a terminal screw ll. Said strap serves to conduct current through the switch casing without passing through the contact members. I

The strap 48 extends-to the center of the There is also a fourth and,

arcuatelineoi'contactmembers andapivotpin" ll'for the switch is passed there- I only the stationary contact member Said pivot pin is preferably a tubular eyelet which is headed over saioi strap.

The switch mechanism is located upon the front face of said insulatingsupporting plate and lnclucles a movable contact member 52 anol an actuating member 56.

Sold actuating member 56 comprises a gen= erally flat plate, oi triangular shape, having an aperture 56 intermediate its ends in which the pivot pin on loosely fits. Said plate is pivoted on seici pin and is supported in elevated position above the face of the insulating plate by a cupshaperi washer 58, the base of which rests upon eairl insulating plate anol the convex face of which is engaged by said actuating plate. The small enci of said actuating plate is terminated in a rectangular shank which is of substan= tial length anti is refiexeci upwardly at general right angles with the plane of the plate and. is extended movably through the arcuate slot it or the casing and corriesthe actuating button it]. The plate is curved in a general downward direction or toward the supporting plate and has a loot 62 which underlies the base of the shanlr (iii anti upon and ricles over the race of the insulating plate so as to provide a good support for the tree enti of the plate.

The movable contact member 52 is made from. a resilient thin metal plate and. is bell-crank shaped. or is proviolecl with a pair of integral wiclely angularly spaced contact arms (it and the is adapted to engage the sta tionary contact members 22, 26, 2b and is longer than the 66 which is adapted to engage The arms are so angularly related that when the long arm G lls engaged with contact member 26, the short arm 66 is simultaneously engaged with contact member 28. In all other positions of long contact arm the short arm is :free from engagement with any stationary contact member. when both arms are engaged with corn tact members '28 and 28 the two heater elements m and Bil, see Fig. 7, are connected in parallel to the line conductors, thereby providing for maximum heat output of the heating The movable contact member o2 is provldecl with an aperture l2 through which the pivot pin 5b is extended loosely, the head it or the pin overlying the contact member and thus retaming it and also the actuating arm and washer 58 in position. The washer 58 preferably exerts a slight amount of pressure between the actuating and movable contact members and the head or the pivot pin, so as to ensure good electrical connection between the movable contact member and the strap 46, although the pressure is not so much as to interfere with the free snap movement of the mechanism as will be presently described.

The long arm 64 of the movable contact member is provided with a rectangular aperture 82 conformed to the cross-sectional shape of the shank 60 of the actuating plate 54 and through which said shank is freely extended whereby to connect the plate and arm for conjoint angular movement, there being sufllcient freedom of fit to permit the long arm 64 of the movable contact member to move up and down or flex freely in riding 'over its cooperating contact members although there is not so much looseness as to give a deleterious amount of independent angular movement of the contact member and actuating plate.

The free end of the long contact arm 641s bent permanently in the direction of the cooperating contact members so that the end thereof is pressed firmly and resiliently into engagement therewith. The free end is provided with a c0ntact boss 84 having a generally semi-spherically shaped face that is adapted to seat yieldlngly in the tubular encl faces of the stationary contact members.

The short contact arm 66 is also bent in the direction of its cooperating contact member and the free end thereof is provided with a similar contact boss 86. When said boss is not engaged with the contact member 28 it is resiliently engaged with and rides over and in contact with the lace oi the insulating supporting plate.

-With the arrangement described a generally three-cornered support is provided; for the movable switch member and the engagement of one contact arm with its stationary contact member does not weaken the firmness oi the engagemerit between the other arm and its stationary contact member. Neither is the engagement affected by the actuating plate since the movable swltch member is supporteol independently thereof.

The switch is provided with mechanism which holds the movable switch mechanism yieldingly in any set position thereof and which effects the rapid or snapmovement of the switch mechanism from one position. into the next adjacent position. To this end the broad edge of the actuating plate 5 3 is provided with an arcuate series of closely positioned semi-circular notches or indentations 38 and. sharp-ended teeth or projections St between the notches, there being a notch'for each or the three circuit-engaged positions of the movable switch member and. two additional notches located at the ends of the series of notches and corresponding to circuit open positions of the switch member.

Said notches are adapted to be engaged, one at a time, y a retaining member comprising a plate 92 secured by rivets 94 to the supporting plate and having an upstanding free resilient arm 95 which confronts the series of notches and has a semi-cylindrical projection 96 that conforms generally to the shape of a notch and is adapted to enter a notch positioned in reglster therewith and bear with the inherent spring pressure of it's arm EM against the end of the actuating plate, whereby to hold the plate releasably in set position. Pressure on the plate tending to move the plate angularly is at first opposed by the resilient arm, which, upon sulficient pressure, suddenly yields permitting movement of the plate until a projection passes the center line of the arm projection 96 whereby the arm springs into the next notch, forcing the actuating plate angularly in the direction of the application of pressure. This results in the rapid or snap opening of one circuit and the rapid or snap closing of the next circuit.

I claim:

1. An electric switch comprising a supporting plate, a plurality of stationary contact members carried thereby and arranged in an arcuate series in a group. another stationary contact member carried by said plate remote from said group, a pivot pin in said plate, a movable switch member on said pin consisting of two divergent resilient arms extended laterally of said pivot pin on the same side thereof one cooperating with said group of contact members and the other cooperating only with said other contact member, an actuating plate pivoted on said pivot pin and disposed be- .tweensaidmppm'tingplateandswitehmmber,

oneotsaidarnuhaviuapcrtorationtherethrowh,andsaid'actuatingplatehavhnaswltch operating shank at the end thereof which upstandsthroughsaidpm'iorationandconnectssaid actuatingplateandswitchmunber iorconioint "angularmovementsaidpm'i'oratcdarmandsaid -carriedbysaidplateremotefromsaidgroup,a

- in a group, another pivot pin in said plate, a movable switch member on said pin consisting of two divergent resilient armsonecooperaflngwithsaidgroupoicontact members and the other cooperating only with said other contact member, an actuating platepivotedonsaidpivotpinanddispoaedbetween said supporting plate. and switdi member andunderone onlycisaidarmatheotherof said arms being extended laterally oi. said actuating plate, means connecting said actuating plate and switch member for conjoint angular movement, anactuatinghandlecarriedbysaidmeans, said connecting means admitting free movent of saidswltchmunberinaverticaldirectiontoward and away from said supporting plate, said actuating plate having a series of arcuately arranged closely spaced notches in one edge thereof, and aspringarmcarriedbysaidsupportingplate having a cam projection resiliently retained re: leasably in any one'of said notches.

3. An electric switch comprising a supporting plate, a morality of stationary contact munbers carried thereby and arranged in an arcuate series 7 contact member carried by said plate remote iromsaid group, a pivot pin in said phte. a movable switch member on said pin condsting of two divergent resilient armsextendedlaterallyofsaidpivotpinonthe samesidethereofmec'ooperatingwithsaidgroup of contact lnembers and the other cooperating only with said other contact member, each of saidarmsprovidingsupport'iortheotherarm, an actuating plate ravoted onsaidravot pin and dlspmed'between said supporting plate and switch member, said actuating plate having an upstanding no'rmally-engageable shank which projects looselythroughanarmofaaidswitchmemberand constitutes means connecting said switch member and arm for conJdnt angular movement, and an pivotedonmid avotplnanddispoaedrmderaaid switch member. Idllentplate apaciu ms onsaidplnunderaaidaehntingphtem to a'mmidaehmtiryphteandswltehmanber into yielding engagement, said actuating plate having an upturned switch-operating shank which loosely passes through and engages an arm of said switch member and constrains it for con- Joint angular movement with said actuating plate, said actuating plate at said shank end thereof having a depressed part that engages and rides over the lace of said supporting plate.

5. An electric switch comprising an insulating supporting plate, a pivot pin therein, a seri of stationary contact members arranged in a close positioned group in arcu'ate order in said plate about said pin, another stationary contact member carried by said plate remote from said group, an actuating plate pivoted intermediate its ends on said pivot pin, said actuating plate at one end having an upturned manually engageable switch-operating shank, a switch member -on said pivot pin consisting of a resilient metal plate having a pair of divergent resilient contact arms, one for engagement only with said group of contact members and the other for engagement only with said other contact member, one of said arms overlying a part of said actuating plate and having an aperture therethrough through which said shank is passed loosely whereby to connect said actuating plate and. switch member for conjoint angular movement, said apertured contact arm being free to flex toward and away from said supporting plate, said other arm extended laterally of said actuating plate, the free ends of said arms being bent into contact with said supporting plate whereby said switch member is provided with a three-cornered stable support for angular movement, the end of said actuating plate remote from said shank and on the other side of said pivot pin being elevated above said supporting plate and having an arcuate series of closely spaced notches therein, and a spring arm carried by said plate having a cam projection pressed yieldingly into any one of said notches.

6. A cord type electric switch comprising a supporting base, a pivot pin carried by said base. a movable resilient bell-crank switch member on said pin, separate stationary contact members engageable by separate resilient arms of said switch member, a movable actuating plate on said p n and under said movable switch member and having a part underlying one only of said arms, the other am being extended laterally of said plate, said underlying part having an upstanding member extended loosely through the overlying arm, and a manually-engageable plate-actuating part above said overlying arm.-

7. A cord type electric switch comprising a supporting base, a pivot pin carried by said base, a movable resilient bell-crank switch member on said pin, separate stationary contact members engageable by separate resilient arms of said switch member, a movable actuating plate on 'said pin and under said movable switch member and having a part underlying one only of said arms, the other arm being extended laterally of said plate, said underlying part having an upstanding member extended loosely through the overlying arm, a manually-engageable plate-actuating part above said overlying arm, said actuating plate having peripherally notched sections on the side of said pivot pin opposite said underlying part, and a spring-urged member releasably retainable in said notches.

FREDERICK m 

